OBJECTIVE: To test whether complications happen more often with the internal jugular or the subclavian central venous approach. DATA SOURCE: Systematic search (MEDLINE, Cochrane Library, EMBASE, bibliographies) up to June 30, 2000, with no language restriction. STUDY SELECTION: Reports on prospective comparisons of internal jugular vs. subclavian catheter insertion, with dichotomous data on complications. DATA EXTRACTION: No valid randomized trials were found. Seventeen prospective comparative trials with data on 2,085 jugular and 2,428 subclavian catheters were analyzed. Meta-analyses were performed with relative risk (RR) and 95% confidence interval (CI), using fixed and random effects models. DATA SYNTHESIS: In six trials (2,010 catheters), there were significantly more arterial punctures with jugular catheters compared with subclavian (3.0% vs. 0.5%, RR 4.70 [95% CI, 2.05-10.77]). In six trials (1,299 catheters), there were significantly less malpositions with the jugular access (5.3% vs. 9.3%, RR 0.66 [0.44-0.99]). In three trials (707 catheters), the incidence of bloodstream infection was 8.6% with the jugular access and 4.0% with the subclavian access (RR 2.24 [0.62-8.09]). In ten trials (3,420 catheters), the incidence of hemato- or pneumothorax was 1.3% vs. 1.5% (RR 0.76 [0.43--1.33]). In four trials (899), the incidence of vessel occlusion was 0% vs. 1.2% (RR 0.29 [0.07-1.33]). CONCLUSIONS: There are more arterial punctures but less catheter malpositions with the internal jugular compared with the subclavian access. There is no evidence of any difference in the incidence of hemato- or pneumothorax and vessel occlusion. Data on bloodstream infection are scarce. These data are from nonrandomized studies; selection bias cannot be ruled out. In terms of risk, the data most likely represent a best case scenario. For rational decision-making, randomized trials are needed.